It is generally known for a camera to include a rotatable film winder that coaxially engages the slightly protruding end of a film spool inside a film cartridge in the camera, to rotate the film spool in order to wind a filmstrip onto the film spool. The film spool is incrementally rotated after each exposure to wind successive exposed frames of the filmstrip into the film cartridge. Alternatively, the film spool is continuously rotated after the last exposure to wind the entire length of the filmstrip into the film cartridge. Typically, the film winder is retractable from the slightly protruding end of the film spool to facilitate film loading (or unloading), i.e. cartridge loading, into the camera.
Often, as described for example in prior art U.S. Pat. No. 3,602,121 issued Aug. 31, 1971, and U.S. Pat. No. 4,887,114 issued Dec. 12, 1989, a latch member is movable into engagement with a film door to a chamber for the film cartridge in order to secure the film door closed and is movable out of engagement with the film door in order to permit the film door to be opened for film loading. The latch member is mechanically connected with the film winder to retract the film winder from the slightly protruding end of the film spool when the latch part is moved out of engagement with the film door.